here’s why processionary caterpillars are very stinging


“I have large patches of pimples on the inside of my thighs and on my stomach. I had to get up at night to take an antihistamine pill to calm the itch,” says Anne, 35 years old. “Me, I have it all over my neck! I scratch myself to the point of blood,” replied Marine, a friend with whom she was on weekends in the department of Aisne. “It’s very enjoyable to scratch,” retorts another friend of the group, to play down the situation.

The processionary caterpillars have invaded the Paris basin, Picardy, Lorraine and even Alsace in recent weeks. Whether you live there or go on vacation, beware … You will surely be “scratching” … all summer long.

What do these caterpillars look like?

Processionary caterpillars are known for their gregarious lifestyle and movement in single file.

In adulthood, the caterpillar turns into a butterfly. Its larva takes the form of a caterpillar that can measure up to 40 millimeters in length, the body dotted with red spots and the yellow belly, explains the Regional Health Agency (ARS) of the Grand Est.

At the moment, it is rather the oak caterpillars that are active, explains Dr. Sandra Sinno-Tellier, assistant to the director of health alerts and vigilance and toxicovigilance coordinator at the National Agency for National Food Safety (Anses ). Indeed, pine caterpillars appear earlier in the year.

Where are they?

If we can’t see them, where are they? Oak caterpillars stay in trees and feed when they emerge from the nest after winter. In the trees, they create their cocoon of white silk before transforming into a moth. The pine processionary caterpillars will burrow into the ground to make their chrysalis before transforming into a butterfly. These are the caterpillars that we see in single file.

The areas of eastern France are endemic. They’ve been there for a very long time. The milder temperatures allow the caterpillars to survive especially during the winter period.

Why should we fear them?

A story of hair. Caterpillars not only develop characteristic long silky hairs, but also microscopic hairs contained in glands that can be ejected when the animal is stressed. These are the ones who are extremely stinging. “The caterpillars, when they feel threatened, unfold the segments of their body and release stinging hairs, invisible to the naked eye. These hairs correspond to microscopic needles which contain a toxic protein”, continues Sandra Sinno-Tellier. “They implant themselves in the skin and release the protein when they break.”

Contact with these caterpillars and their nests should be avoided. But no matter what, if you find yourself in an infested area, you probably won’t escape an allergy. Indeed, the hairs of the caterpillars come off and fly in the air until it lands on your skin. “Exposure to the stinging hairs of caterpillars is most often done indirectly”, summarizes the specialist.

How to protect yourself from it?

The more you are exposed to a nest, the more likely you are to be allergic to the toxic protein in stinging hairs.

ANSES provides access to its website advice to limit the risks: do not approach or touch the caterpillars, do not walk under a tree carrying a nest, wear protective clothing (sleeves and long pants, headgear and possibly glasses), avoid rub the eyes in the event of exposure but also during and after returning from a walk, take a shower and change clothes or even wash the fruits and vegetables in your garden in the event of an infestation nearby.

Also, it is not recommended to dry the respiratory masks used in the context of the Covid-19 epidemic outdoors.

What are the consequences ?

“Very intense irritations of the skin and mucous membranes (itching, conjunctivitis, irritative coughs, etc.) are then triggered, but also sometimes allergic reactions (hives, breathing difficulties, etc.), which will become more and more severe if contact with the allergen are repeated “, warns the ARS again.

Not enough to confuse these buttons with those of mosquitoes: the caterpillars cause an urticaria reaction. The itch is very intense. Pimples due to caterpillar hairs are accompanied by red patches. Mosquito buttons are more localized.

What if you have been exposed to these stinging hairs?

Take antihistamines that will give you relief. Avoid a hot shower which will reactivate the toxic protein but prefer a cold water cloth to calm the itch. Apply cortisone cream if needed. You can use sticky paper to remove these invisible hairs.

And above all, be patient: the plaques will only leave after 48/72 hours.


Source: Le Progrès : info et actu nationale et régionale – Rhône, Loire, Ain, Haute-Loire et Jura | Le Progrès by www.leprogres.fr.

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